Abi was busy meditating in his dressing room, when Sebastian barged in, and told him it was time to practice his act. He told Sebastian that he is impervious to inure cynicism, but, after being threatened to get permanently disembodied from the entire show, suddenly gave in.
In Abi's act, he sits on a bed of nails, plays a clarinet to charm a snake (who is really Arthur wearing a turban), and does a few yoga techniques. While he was trying to bend over between his legs, he fell off the bed, and managed to get his head stuck in his rectum, and was unable to get it out. This made Sebastian (who, rudely, thought that it was part of the act) say that if that was supposed to happen, they could call it, "Passage to India."
Later on, during Heidi's rampage (and Sebastian's performance of "the Sodomy Song"), Abi managed to get his head out of his rectum, but then got crushed to death by the bed of nails (which fell off of a pile of props).